| 摘要 |
An evacuating pump has a hollow cylindrical body, a cap at one end of the body, and a nozzle at the opposite end. A plunger disposed within the body has a piston attached to an inner end of a reciprocating rod, while the outer end of the rod extends through a bore provided in the cap. When the plunger is withdrawn, a vacuum is created at the nozzle, while on the inward stroke, a check valve flap seats over the nozzle inlet to prevent air from being injected through the nozzle. Air being compressed on the inward stroke escapes around the peripheral edge of the piston.
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